System electrical parameters and their effects on bearing currents

Author

Busse, Doyle ; Erdman, Jay ; Kerkman, Russel J. ; Schlegel, Dave ; Skibinski, Gary

Author_Institution

Rockwell Autom.-Allen Bradley Co. Inc., Mequon, WI, USA

Volume

33

Issue

2

fYear

1997

Firstpage

577

Lastpage

584

Abstract

This paper examines AC motor shaft voltages and resulting bearing currents when operated under pulse width modulation (PWM) voltage source inverters. The paper reviews the electrical characteristics of bearings and motors that cause shaft voltages and bearing currents. A brief review of previous work is presented, including a system model for electrical analysis of bearing currents. Relying on the work of a companion paper, the propensity for electric discharge machining (EDM) is determined by a design equation that is a function of system components. Pertinent machine parameters and their formulas are presented and values calculated for machines from 5 to 1000 HP. The effects of system elements on shaft voltages and bearing currents are evaluated experimentally and the results compared to theory. Finally, the paper presents quantitative results for one solution to the shaft voltage and bearing current problem

Keywords

AC motors; PWM invertors; equivalent circuits; machine bearings; spark machining; 5 to 1000 hp; PWM VSI; PWM voltage source inverters; bearing capacitance; bearing currents; bearing threshold voltage; bearing voltage ratio; common mode equivalent circuit; electric discharge machining; electrical analysis; electrical characteristics; electrostatic shielding; pulse width modulation; rotor; shaft voltages; stator; system electrical parameters; AC motors; Capacitance; Electrostatics; Induction motors; Machining; Pulse width modulation; Pulse width modulation inverters; Rotors; Shafts; Threshold voltage;

fLanguage

English

Journal_Title

Industry Applications, IEEE Transactions on

Publisher

ieee

ISSN

0093-9994

Type

jour

DOI

10.1109/28.568025

Filename

568025